<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>函数部分</title>
<script type="text/javascript">
	function getSum(x, y) {
		//alert(arguments.length);
		return x + y;
	}
	alert(getSum());//NaN
	alert(getSum(3));//NaN
	alert(getSum(3, 6));//9
	alert(getSum(3, 6, 7));//9
</script>
</head>
<body>
	<script type="text/javascript">
		alert(arguments.length);//不显示
	</script>

</body>
</html>